​Pigs can be incredibly challenging pets… and once they have learned a few bad behaviors they can seem downright impossible. As we all know, pigs are exceptionally smart and can also seem unbelievably stubborn; successfully changing behaviors can be time-consuming and frustrating. On top of that, often when we try and change a behavior, it seems to get even worse! Today I'll be addressing extinction events and variable ratio of reinforcement - understanding these concepts will go a long way in helping us maintain our resolve, and hopefully sanity, as we work through problem behaviors with our pigs. Let’s consider a common scenario with a housepig:
 
Pig wakes us up every morning at 4am by screaming and we give him his breakfast to get him to be quiet. How do we stop Pig from waking us up every morning? Well, in order to change problem behaviors, we need to first identify HOW the bad behavior is being reinforced (remember: if you have a pig that displays problem behaviors, the behaviors are SOMEHOW being reinforced. It may not be obvious at first, but animals don’t continue to repeat behaviors that don’t receive reinforcement). So let’s say that we have identified the reinforcer – feeding Pig when he screams at 4am. So we either completely stop reinforcing it or greatly reduce how often we reinforce it, and… It doesn’t have any effect  - or more commonly, the bad behavior gets EVEN WORSE than before. What went wrong? First, let’s consider a different scenario that might be a little more familiar:
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We have a laptop computer. We go to turn it on one day and it doesn’t turn on. Do we immediately assume that it’s broken and give up? Of course not- we would certainly try several more times to get it to turn on. Our actions (turning on the computer) have been rewarded consistently in the past (the computer turns on), so we have received reinforcement that it SHOULD work. What happens if our computer is older and has a history of being finicky about turning on? We would likely try EVEN LONGER to get it to turn on before giving up, because we know eventually, our actions will probably be rewarded and the computer will turn on.
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These same learning principles apply regardless of species. So back to Pig –  remember, Pig wakes up at 4am every morning and we now know that by feeding him, we are reinforcing that behavior. So we decide that we will ignore him when he screams. The next night, Pig starts screaming at 4am. We ignore it, but it doesn’t stop. In fact, Pig screams EVEN louder now! Why is this? Pig is demonstrating an extinction event, or extinction burst. When a behavior that was rewarded previously is no longer rewarded, Pig will initially perform that behavior even more intensely or vigorously than before. Remember the above example of our computer not turning on! It is no different for Pig – he assumes that maybe we just can’t hear him, or maybe if he screams JUST A LITTLE LONGER, he will finally get food (and depending upon the behavior, it can take days, weeks, or even longer to see a change).
 
So what if we work really hard to ignore pig for several nights, but in a few days, we are exhausted and we just need him to be quiet so we can get some sleep, and so we give in just once? What if we only give him a treat every now and then, but not every time he screams? We might think to ourselves, 'well, surely the behavior will decrease because I’m only giving in occasionally and so Pig isn’t being rewarded all the time.' This is VARIABLE RATIO OF REINFORCEMENT, and it is actually even more powerful as a reinforcer than continual reinforcement. Remember how our laptop is finicky and sometimes takes a while to turn on? Because of this, we are MORE persistent with our attempts to turn it on. Pig is no different – if he is occasionally rewarded, he will persist EVEN MORE with the behavior that sometimes gets him treats.

In fact, variable ratio of reinforcement is one of the reasons why punishment tends to be so ineffective with pigs. ESPECIALLY if the reinforcer is food, there is almost no punishment that would be severe enough to stop a pig from continuing to try to obtain it, even if they know punishment is likely. If your pig snaps and grabs for food in your hand when you’re sitting on the couch, and 9 times out of 10, you scold him and push him away, but every 10th time he tries it, he manages to get a piece before you deliver the punishment, he WILL be on a schedule of variable rate reinforcement, and he WILL continue to do the behavior. You have simply turned your pig into a gambler. Unfortunately with pigs, they are also smart enough to know that 9 times out of 10, they will receive punishment instead of the reward, which makes them proactively aggressive and anxious, because now that behavior not only occasionally leads to rewards, but other times, that very same behavior leads to punishment. It makes for a very frustrated, confused, aggressive pig. The single most effective method for stopping bad behaviors is to remove the chance for reward 100% of the time. It can’t be 97%, or 98% or even 99.9%- that’s not good enough with pigs. That might mean fundamental changes to your household. Maybe pig isn’t ever allowed in the kitchen & dining area, and that is the ONLY place where people-food is allowed (no one ever said house-pigs were easy!).
 
(Here’s something else to consider:  Do you have a friend who is sometimes super fun to hang out with but other times is a total jerk? Why do you continue to spend time with this person? Because you are on a schedule of variable ratio of reinforcement – when you hang out with your friend, you hope that you will get lucky and this time will be fun…  and even if it isn’t, you know that next time might be!)
 
Why do we spend time at the casino when we know that our chances of being rewarded are extremely low? Why does Pig keep trying to get into the garbage even though he only occasionally succeeds? Because variable ratio of reinforcement is incredibly powerful, whether we’re a person or a pig.
 
When it comes to behavior, we’re all gamblers at heart.

In a fascinating study of young pigs, researchers found that pigs that were pushed away when they tried to make physical contact with a handler did NOT show a decrease in their attempts to continue to make contact. However, these pigs DID show an increase in frustration-based behaviors. The potential implications of this finding with regard to how we deal with problem behaviors in pet pigs is significant.

In this study, Repeated Handling of Pigs During Rearing. I. Refusal of Contact by the Handler and Reactivity to Familiar and Unfamiliar Humans, researchers looked at pig behavior in the presence of humans under different handling treatments. The groups of pigs were designated as follows: Human Interaction (HI), Refusal of Contact (RC), and a third control group that received no contact. The pigs in the experiment were 11 week old castrated males and the experiment lasted 40 days. For the pigs in the HI (human interaction) group, the handler tried to encourage physical contact through a predetermined protocol, starting with using voice and progressing to mutual physical contact and play ("Behavioral indications of acceptance were the following: nibbling the handler’s hand (in response to catching of the pig’s rooting disk), shaking its head (in response to catching the pig’s ears), active participation in play (pig catches sleeve and shakes the handler’s arm, pig catches zip of overalls, etc."). For the pigs in the RC (refusal of contact) group, the handler discouraged any physical contact - if the pig made physical contact with his nose, he would be pushed away. If he tried to nibble on coveralls or zippers, he would receive a tap on the nose. As we might expect, the researchers found that over time, the HI pigs increased physical contact (up to 35% of their time) with their handler. More interesting though, is that the researchers also found that the RC pigs maintained the same frequency of attempts at physical contact with their handler over the course of the experiment, even though they were pushed away any time they tried to initiate contact:

"Motivation to interact with the handler was high even for RC pigs. Although these pigs were consistently pushed away whenever they established physical contact with the handler, they persisted in trying to establish contact throughout the experimental period, and as often as HI pigs. Their interest in the handler is further underlined by the fact that, when in the pen half away from the handler, they were oriented toward her as often as HI pigs, and that during locomotion, they oriented more often toward her than HI pigs."

While the frequency of attempts at physical contact by the pigs didn't decrease over time, the researchers did find an INCREASE in frustration-based behaviors by these pigs...

"Compared with HI pigs, RC pigs showed more snout contact with the wall, rubbing, locomotion, and immobility. Pigs of the RC group showed a shift in activities over treatment weeks. Levels of immobility were higher from the first recording day onward and showed a nearly fourfold increase over the treatment period, whereas locomotion and rubbing decreased. Increased levels of these activities compared with HI pigs may be partly explained by an altered time budget, as the pigs were denied continuous contact with the handler. Increased oral activity, locomotion, and immobility have further all been observed in various aversive situations, believed to cause frustration (see above; Vestergaard, 1984; Dantzer et al., 1987; Terlouw et al., 1991; Bishop et al., 1999; Lewis, 1999). The shift toward immobility may be caused by the increasing certainty on the part of the pigs that contact with the handler would not be allowed, resulting in increasing frustration."

What does this study mean for us? There are a couple of really interesting takeaways. Firstly, domestic pigs, by their very nature, tend to seek out humans.  However, piglets don't inherently know appropriate behaviors with people and sometimes bite, jump or otherwise engage too roughly (much like an exuberant puppy). Unfortunately, if we interpret these behaviors as dominance or use punishment to try and correct them, it can seriously affect future behavior. Of course, in this study, the pigs in the RC (refusal of contact) group were pushed away ANY time they attempted to make contact - our pet pigs hopefully would not encounter this level of distance from their owners. But often pet pig owners use these methods, at least in part, to manage behaviors of pigs, and this offers some insight into how pigs respond when presented with this type of treatment. It is also important to note that in the HI group, pigs were not discouraged or punished for nibbling hands or rough play, because these are signs of behavioral acceptance. While we may not want to encourage these specific behaviors in pet pigs, we certainly don't want to discourage pigs that are showing acceptance of us! Especially if we are dealing with a young pig that is curious about people but doesn't understand how to interact properly (nips, jumps or engages in other inappropriate behaviors), it becomes essential to help the pig understand what IS expected of him. Using punishment like pushing him away doesn't teach him what he SHOULD do, and can lead to significant frustration for the pig. Two things of note:
 
          1- Pigs who get pushed away from their handlers show more behaviors associated with frustration, such as standing immobile, nosing the floor or wall, etc. While this study was relatively short (40 days), frustration behaviors in pigs can shift over time - so if we push our pig away when they behave inappropriately or to show dominance over the course of months to years, it is certainly possible these frustration-based behaviors would intensify or worsen over time.

          2- The more interesting finding of this study is that pushing the pigs away when they made physical contact with the handler DID NOT decrease the attempts at physical contact by the pig! If you push your pig away because he is behaving inappropriately or to show dominance, the pig may well keep attempting to make physical contact, all the while becoming increasingly frustrated and anxious because he doesn't understand why he is being punished. More significantly, if light shoving doesn't discourage the pig, you may escalate to more forceful methods, which in turn can lead to fearful responses by the pig that have the potential to turn into fear-related aggression in the future.
 
Of course, this doesn’t mean that you need to let your pig make physical contact with you anytime he wants. Boundaries are important for pet pigs, but the single most effective way to manage problems with pet pigs is to prevent the unwanted behaviors from happening in the first place, and short of that, redirecting your pig to a more appropriate behavior or action if you notice him doing something unwanted. You can use a crate, kiddie gates, or put your pig outside if you don’t want him bothering you. If your pig behaves inappropriately when he interacts with you by being too mouthy or pushy, you might use methods like positive reinforcement and negative punishment to help your pig learn the proper way to interact with people (check out the Case Studies page for more information).

​Terlouw, E. , & Porcher, J. (2005). Repeated handling of pigs during rearing. i. refusal of contact by the handler and reactivity to familiar and unfamiliar humans. Journal of Animal Science, 83(7), 1653-1663.

​​I wanted to share some particularly interesting research on pigs regarding generalization behaviors. Pigs (and other animals) learn from experiences by either generalizing or by discriminating - generalizing is the ability to learn something in one context and apply it to other situations, discrimination is learning something and only applying it in the narrow context in which it was learned. Often with prey species, generalization is an important ability with regard to fear-responses because it allows the animals to recognize potentially dangerous situations after only a single or very few encounters. If a prey animal narrowly escapes a predator in one context, it is important to be able to generalize out to other contexts so that the prey animal responds appropriately in the future. In this study (Hemsworth et. al.,1994), researchers found that "in situations in which pigs are briefly handled by one of two stockpersons in a predominantly negative manner or in which pigs are briefly handled by stockpersons who differ markedly in the nature of their behaviour towards pigs, pigs are likely to exhibit stimulus generalization as measured by their behavioural responses to humans." In other words,  pigs learn to associate rough handling from their specific handler, and subsequently responded to any humans in the same manner, by practicing avoidance or fearful behaviors. This makes sense, because as a prey species, it is important for pigs to recognize and remember when something unpleasant happens and to be able to apply that knowledge to future situations.  Keep in mind that an aversive is ANYTHING the pig finds unpleasant - WE might know that a light shove or push doesn't actually hurt the pig, but if the pig finds it unpleasant, it IS classified as an aversive.

If we use aversive techniques like dominance theory, the pig is likely to generalize his rough handling out to all people. There is a strong anecdotal correlation between homes that utilize methods of force or intimidation to manage problem behaviors and the presence of reactive behaviors from those pigs towards guests and unfamiliar people in the home. Have these pigs generalized their rough handling and learned that all people are unpredictable, frightening and perhaps dangerous?

(ETA): Interestingly, studies also show that while pigs generalize bad experiences, they tend to behave discrimanatorially with regard to postive experiences (ei they won't immediately associate all people with good things if one person treats them well - I'll be discussing those studies in more depth in a future post). It seems it is very easy to lose a pig's trust, and much much harder to regain it.